Tag Archives: Ventilator

What are ‘iron lungs’, and could this old tech still be useful today?

Although they’re relatively old technology in this day and age, there is renewed interest in iron lungs today against the backdrop of the coronavirus pandemic.

An iron lung device. Image credits The B’s / Flickr.

Few devices can boast having as terrifying — and cool — a name as the iron lung. These somewhat outdated medical devices were the earliest devices designed to help patients breathe. Compared to modern breathing aides, these devices were huge and quite scary-looking.

Still, iron lungs were a very important development at their time. In the aftermath of the COVID-19 epidemic, there has also been renewed interest in these devices as they can be used as an alternative to modern ventilators.

So let’s take a look at exactly what iron lungs are, and how they came to be.

So what are they?

Iron lungs are quite aptly named; unlike other modern ventilators, they function using the same mechanisms as our own lungs.

An iron lung is a type of negative pressure ventilator. This means that it creates an area of low-pressure or vacuum to move and draw air into a patient’s chest cavity. In very broad lines, this is the exact mechanism our bodies employ, via movements of the diaphragm, to let us breathe.

The concept behind these devices is quite simple. The main component of an iron lung is a chamber, usually a metal tube (hence the ‘iron’ part in its name) that can fit the body of a patient from the neck down. This acts as an enclosed space in which pressure can be modified to help patients breathe. The other main component of the device is mobile and actually changes the pressure inside the tube. Usually, this comes in the form of a rubber diaphragm connected to an electrical motor, although other sources of power have been used, including manual labor.

Patients are placed inside an iron lung, with only their head and part of their neck (from their voice box upwards) left outside the cylinder. A membrane is placed around their neck to ensure that the cylinder is sealed. Afterward, the diaphragm is repeatedly retracted and contracted to cycle between low and high pressure inside the chamber. Because the patient’s head and airways are left outside of the cylinder, when pressure is low inside it, air moves inside the patient’s lungs. When pressure increases inside the cylinder, the air is pushed back out.

The whole process mirrors the way our bodies handle breathing. Our diaphragm muscles draw on the lungs, increasing their internal volume, which pulls air in from the outside. To breathe out, the diaphragm muscle squeezes on the lungs, pushing air out. Iron lungs work much the same way, but they expand and contract the lungs alongside the rest of the chest cavity from outside the body.

This process is known as negative pressure breathing; low (‘negative’) pressure is generated in the lungs in order to draw in air. Most modern ventilators work via positive pressure: they generate high pressure inside the device to push air into the patient’s lungs.

One advantage of such ventilators is that patients can use them without being sedated or intubated. On the one hand this eases the pressure on medical supplies each patient requires; on the other, it slashes the risks associated with the use of anesthetics — such as allergic reactions or overdoses — and the risk of mechanical lesions following intubation.

Epidemics, pandemics

An opened iron lung device at the Science Museum, London. Image credits Stefan Kühn / Wikimedia.

“The desperate requests for ventilators in today’s treatment of patients in the grasp of the coronavirus brought to mind my encounter with breathing machines in the early 1950s polio epidemic, when I signed up as a volunteer to manually pump iron lungs in case of power failure at Vancouver’s George Pearson Centre,” recounts George Szasz, CM, MD, in a post for the British Columbia Medical Journal.

Iron lungs saw their greatest levels of use in developed countries during the poliomyelitis outbreaks of the 1940s and 1950s. One of the deadliest symptoms of polio is muscle paralysis, which can make it impossible for patients to breathe. The worst cases would see patients requiring ventilation for up to several weeks. Back then, iron lungs were the only available option for mechanical ventilation, and they saved innumerable lives.

As technology progressed, however, iron lungs fell out of use. They were bulky and intimidating machines, hard to transport and store despite their reliability and mechanical simplicity. With more compact ventilators, the advent of widespread intubation, and techniques such as tracheostomies, such devices quickly dwindled in number and use. From an estimated height of around 1,200 iron lung devices in the U.S. during the ’40s and ’50s, less than 30 are estimated to still be in use today

There are obvious parallels between those polio epidemics of old and today’s COVID-19 pandemic in regards to the need for ventilation. Machines such as the iron lung have been suggested as a possible treatment option for COVID-19 patients due to this. For most cases, such devices can help, but not for all.

In cases of severe COVID-19 infections, the tissues of the lungs themselves are heavily affected. A buildup of fluid in the lungs can physically prevent air from reaching the alveoli (the structures in the lung where gases are exchanged between the blood and the environment). While iron lungs can perform the motions required to breathe even for patients who are incapable of doing it themselves, they cannot generate enough pressure to push air through the tissues affected by a COVID-19 infection.

“Iron lungs will not work for patients suffering from severe COVID-19 infections,” explains Douglas Gardenhire, a Clinical Associate Professor and Chair of Respiratory Therapy at the Georgia State University (GSU) Department of Respiratory Therapy. “Polio interrupted the connection between brain and diaphragm and while some polio patients did have pneumonia, it was not the principal issue. For the most part, the lungs themselves did not have any change in their dynamic characteristics.”

“COVID-19 pneumonia physically changes the composition of the lungs,” adds Robert Murray, a Clinical Assistant Professor at the GSU. “The consolidation of fluid in the lungs will not respond with low pressure generated by the iron lung. The lungs of a COVID-19 patient will be a heterogenous mix of normal and consolidated lung tissue making mechanical ventilation very difficult.”

Still an alternative

Although patients with severe COVID-19 infections might not benefit from the iron lung, there are cases in which the device can prove useful. One paper (Chandrasekaranm, Shaji, 2021) explains that there still is a need for negative pressure ventilators in modern hospitals, especially for patients who have experienced ventilator-induced lung injuries. The use of negative pressure ventilators, especially in concert with an oxygen helmet, may also play a part in reducing the number of infections by limiting the spread of viruses through contaminated materials in cases where resources are stretched thin, the team adds.

While the concept is being retained, however, the actual devices are getting an upgrade. One example is the device produced by UK charity Exovent, which aims to be a more portable iron lung. Exovent’s end goal is to provide a life-saving device that will impose fewer limits on what activities patients can undertake. A seemingly-simple but still dramatic improvement, for example, is that patients can use their hands to touch their faces even while the Exovent device is in operation. Eating or drinking while using the device is also possible.

Exovent’s ventilator was designed before the coronavirus outbreak to help the millions of people suffering from respiratory issues including pneumonia worldwide. However, its designers are confident that, in conjunction with oxygen helmets, it can help patients who are recovering from a coronavirus infection — a process that leaves them with breathing difficulties for months.

All things considered, iron lungs have made a huge difference for the lives of countless patients in the past, and they continue to serve many. Although most of them today look like archaic devices, engineers are working to update and spruce them up for the modern day. And, amid modern ventilators, there still seems to be a role — and a need — for devices such as iron lungs.

NASA developed a new ventilator for COVID-19 patients in just 37 days

We’re living unprecedented times and NASA has been asked to help in the crisis. It did.

Although NASA is typically tasked with space-related missions, the agency’s immense engineering expertise can be applied to all sorts of technologies, solving all sorts of problems.

In just 37 days, the men and women at NASA’s Jet Propulsion Laboratory in Southern California who would normally work on putting rovers on Mars or designing new machine systems for spacecraft worked on something else. They have designed, built, and successfully tested a prototype for a new mechanical ventilator.

The Ventilator Intervention Technology Accessible Locally, or VITAL for short, was developed in record time and recently passed tests at the Icahn School of Medicine at Mount Sinai in New York City on a “high fidelity human patient simulator.”

“We specialize in spacecraft, not medical-device manufacturing,” said JPL Director Michael Watkins. “But excellent engineering, rigorous testing and rapid prototyping are some of our specialties. When people at JPL realized they might have what it takes to support the medical community and the broader community, they felt it was their duty to share their ingenuity, expertise and drive.”

NASA engineers pictured with the VITAL ventilators specifically designed for COVID-19 severe cases. Credit: NASA/JPL-Caltech.

Traditional ventilators that are equipped inside emergency rooms are designed for the intensive care of patients with a broad range of medical issues. They’re built to last for years.

Although similar in many ways, VITAL was designed specifically with COVID-19 in mind. It has fewer parts than a traditional ventilator so it can be manufactured a lot faster and has a designated operating life of only a couple of months rather than years.

“Intensive care units are seeing COVID-19 patients who require highly dynamic ventilators,” said Dr. J.D. Polk, NASA’s chief health and medical officer. “The intention with VITAL is to decrease the likelihood patients will get to that advanced stage of the disease and require more advanced ventilator assistance.”

The VITAL ventilator in operation. Credit: NASA/JPL-Caltech.

Like all ventilators, VITAL requires patients to be sedated and an oxygen tube inserted into their airway to breathe. The prototype passed initial tests with flying colors and is now pending emergency approval by the FDA.

“We were very pleased with the results of the testing we performed in our high-fidelity human simulation lab,” said Dr. Matthew Levin, Director of Innovation for the Human Simulation Lab and Associate Professor of Anesthesiology, Preoperative and Pain Medicine, and Genetics and Genomics Sciences at the Icahn School of Medicine. “The NASA prototype performed as expected under a wide variety of simulated patient conditions. The team feels confident that the VITAL ventilator will be able to safely ventilate patients suffering from COVID-19 both here in the United States and throughout the world.”

A 3D adapter can turn a snorkeling mask into a non-invasive ventilator

If there’s one thing that is in high-demand now across the globe, that’s ventilators. More than 400.000 cases of the virus have left many hospitals without stocks of this key medical equipment, which can help in artificial breathing when lungs fail to do it naturally.

Credit Issinova

Nevertheless, when resources lack, creativity and innovation rise, and that’s what has happened here. Influenced by a large number of cases in their country, a group of Italian engineers has developed and tested a 3D-printed adapter that can turn a snorkeling mask into a ventilator.

This is their second innovative creation since the start of the coronavirus outbreak in Italy. The engineers previously visited a hospital that didn’t have sufficient ventilator valves and, using a 3D printer, developed new ones and printed them in just a few hours. Following that first experience, the team was contacted by the former head physician of the Gardone Valtrompia Hospital.

“He shared with us an idea to address the possible shortage of hospital C-PAP masks, which is emerging as a concrete problem linked to the spread of COVID-19: an emergency ventilator mask,” they said.

The first step was finding a company that produced snorkeling masks and agree on a partnership. That was Decathlon, a French sporting goods company. Once they had the product, the engineers dismantled and studied it to check how to use a valve to connect the mask with the ventilator.

Other designers had already created 3D printable adapters to transform similar snorkeling masks into medical ones. The innovation by the Italian engineers was that the adapter could be modified for the mask to be connected as a ventilator, a key resource needed during the outbreak.

Once they had the new product, they tested it at the Chiari Hospital by connecting it to the ventilator body, proving it worked successfully. They also tested it on a patient with good results. Nevertheless, the invention should only be used in an emergency situation, the engineers warned.

“We are reiterating that the idea is designed for healthcare facilities and wants to help in realization of an emergency mask in the case of a full-blown difficult situation, where it is not possible to find official healthcare supplies. Neither the mask nor the link is certified and their use is subject to a situation of mandatory need,” they said.

The engineers patented the valve that connects the mask and the ventilator so as to avoid speculation on the price. The patent is free as the objective is “that all hospitals in need could use it if necessary,” they said. They also shared the file required to create the valve with a 3D printer, which they claim is easy to manufacture, on their website.

This means that any healthcare facility that needs ventilators can purchase the Decathlon mask and then produce the valve in any local 3D printing facility. “Our initiative is totally non-profit, we will not obtain any royalties on the idea of the link, nor on the sales of Decathlon masks,” they said.

Similar initiatives can be seen in other parts of the world, using 3D printers. In Spain, also severely affected by the outbreak, a group of engineers and doctors have partnered up to develop low-cost respirators and print as much personal protective equipment as possible.